—The Supreme Court agreed Tuesday to jump into a growing legal dispute between businesses run by conservative Christians and the Obama administration over whether a company must pay for birth control drugs that conflict with its owner's religious beliefs.

The decision to hear the case, which could affect millions of women with employer-provided health plans, means that for a second time, the justices will decide the fate of a key part of President Barack Obama's health care law.

Last year, the court in a 5-4 decision upheld the requirement that individuals obtain basic health insurance or pay a tax penalty. The new cases test whether employers who offer insurance may be required to pay for the full range of approved contraceptives, even if they have moral objections to some of them.

Archbishop William E. Lori of Baltimore, chairman of the U.S. Conference of Catholic Bishops' Ad Hoc Committee for Religious Liberty, has been a vocal opponent of mandating companies to provide contraceptives to employees.

The Supreme Court's decision will determine the "freedom of people to practice their faith and put their teachings into practice, not only in the four walls of the church but at work," Lori said Tuesday.

The bishops' committee and hundreds of thousands of Catholics have expressed their concerns to the Obama administration and Congress about the mandate, which they see as an "erosion of religious freedom," he said.

Lori was encouraged by "energy and momentum" he has seen against the mandate but wouldn't speculate on a ruling.

"I don't know how the Supreme Court will decide," the archbishop said. "I'm just gratified that it will be heard."

The case also raises the issue of whether a corporation, rather than an individual, can raise claims regarding religious freedom. In 2010, in the campaign spending case known as Citizens United, the justices ruled that corporations have rights to speech protected by the First Amendment, but they have never said that corporations can claim a religious belief.

The family which challenged the law argues that what's really at stake is their personal beliefs. "Business owners should not have to choose between violating their faith and violating the law," said David Green, founder of the Oklahoma-based Hobby Lobby Inc., a nationwide chain of more than 500 arts and crafts stores with 13,000 full-time employees.

He and his family object to the requirement that they pay for health plans for their workers that cover emergency contraception, including the "morning after" pill and IUDs. Those methods of contraception, by preventing a fertilized egg from developing, amount to abortions, they claim.

They won a ruling from a federal appeals court exempting their company from this part of the law on the grounds that it infringed on their right to religious freedom.

The Obama administration appealed to the Supreme Court and argued that a for-profit corporation has never been accorded personal religious rights. Doing so, administration lawyers said, could open the door to allowing companies to limit many legal rights of workers.

The justices said Tuesday they would hear the Hobby Lobby case and a similar challenge brought by a Mennonite-run woodworking business in Pennsylvania.

White House press secretary Jay Carney said the administration was confident that the court would uphold the law, saying it "seeks to ensure that women and families — not their bosses or corporate CEOs — can make personal health decisions based on their needs and their budgets."

Leading women's rights advocates called the birth-control benefit crucial to workplace freedom for women.

"The contraceptive coverage benefit is a huge step forward for women," said Marcia Greenberger, co-president of the National Women's Law Center. "Bosses have no business meddling in their employees' deeply personal health care decisions."

But defenders of religious rights said these family-run businesses are acting based on their "owners' deep religious commitments" and "are not trying to impose their religious beliefs on anyone," said Notre Dame law professor Richard Garnett. "They are not trying to limit what employees or customers do or believe. They are instead seeking protection against an imposition by the government."

The Affordable Care Act said most employers must provide basic health insurance that covers "preventive services" at no cost to workers. The administration issued a rule saying that the "preventive services" requirement also covers the "full range" of approved contraceptive methods.

When the Catholic bishops complained about the "contraceptive mandate," the White House agreed to exempt "religious employers," including churches. It also said nonprofit, religiously affiliated schools, colleges and hospitals could avoid paying directly for such benefits. Their insurers were told to cover the cost.

Exempting private, for-profit corporations would go too far, however, the administration has said. Dozens of private employers sued, and lower courts have split on the issues involved.

In addition to the question of whether a corporation can claim a religious belief, there is the issue of whether federal law or the Constitution requires that the government give some people a special exemption to some laws over religious beliefs.

The Supreme Court rejected that view in a 1990 opinion by Justice Antonin Scalia. While the First Amendment protects the "free exercise" of religion, he said, it does not give believers a right to ignore laws that apply to everyone.

Congress passed the Religious Freedom Restoration Act in 1993, which said the government "shall not substantially burden a person's exercise of religion," except to further a "compelling" interest.

The court said it would hear both cases in March, meaning it would probably rule in late spring.